JP3221907B2 - Block copolymer resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl aromatic hydrocarbon-conjugated diene block copolymer (hereinafter referred to as "block copolymer") composition having excellent heat stability and color tone stability. It can be used for films, sheets, injection molded products and the like.

[0002]

2. Description of the Related Art Block copolymers having a conjugated diene content of 5 to 40% by weight and compositions thereof are widely used for packaging materials and the like because of their transparency and toughness. It is also used as such. However, block copolymers and their compositions are susceptible to deterioration due to heat during molding, and are liable to cause deterioration in gloss of molded products, generation of fish eyes in films, coloring and the like, and NOX. There is a problem that the color changes to yellow or reddish brown under the atmosphere.

[0003] Such thermal stability and NOX resistance
As one of the measures for improving the performance, 2-t-amyl-6- [1
A combination use of-(3,5-di-t-amyl-2-hydroxyphenyl) ethyl] -4-t-amylphenyl acrylate and a phosphorus-based antioxidant has been proposed (JP-A-2-279756).

[0004]

However, even among the block copolymers, in particular, in the case of a block copolymer having a block ratio of the vinyl aromatic hydrocarbon polymer block of 40 to 95%, Although the impact strength and moldability are relatively good as compared with the block copolymer having a ratio of 100%, there is a problem that heat stability at the time of molding processing is inferior and appearance is remarkably deteriorated. 1,
A block copolymer having a high 2-vinyl content is liable to cause crosslinking and gelling of the conjugated diene, and has poor thermal stability.

Further, the block ratio of the vinyl aromatic hydrocarbon polymer block is 40 to 95%, and the number average molecular weight of the vinyl aromatic hydrocarbon polymer block is 3,000 to 100,0.
In the case of the block copolymer having a 1,2-vinyl content of 15% or more in the microstructure of the conjugated diene, the 2,4-di-t-amyl-6- [1- (3,
5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate or JP-A-2-279756
The combined use of a phosphorus-based antioxidant described in Japanese Patent Application Laid-Open Publication No. H06-27138 is insufficient in the effect of imparting thermal stability, tends to cause poor appearance during molding, and tends to generate fish eyes during film formation. Further, the block copolymer has a problem that the color tone in the desolvation step after the polymerization step tends to deteriorate (yellow), and as a countermeasure, it is known to add an antioxidant before the desolvation step. However, with respect to the resin in the above-mentioned range, the effect of stabilizing the color tone is poor in the system containing the antioxidant.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies and arrived at the present invention.

That is, according to the present invention, in a block copolymer or a polymer mixture containing a block copolymer, the block copolymer has a vinyl aromatic hydrocarbon content of 60 to 95% by weight and a conjugated diene content of 5 to 5% by weight. ~ 40% by weight
The number average molecular weight of the vinyl aromatic hydrocarbon polymer block is 3,000 to 100,000, the block ratio is 40 to 95%, and the 1,2-vinyl content in the microstructure of the conjugated diene is (A) 2-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl]-based on 100 parts by weight of the block copolymer which is 15% or more. 0.05 to 2.0 parts by weight of 4-t-amylphenyl acrylate (B) 0.01 to 1.5 parts by weight of one or more compounds selected from the following phenolic antioxidants 2-t-butyl-6- (3-t -Butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate or 3,9-bis [1 , 1 Dimethyl -2- {β- (3-t
-Butyl-4-hydroxy-5-methylphenyl) propionyloxydiethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane and (C) the following phosphorus-based antioxidant 0.01 to 2.0 wt. Part bis (2,6-di-t-butyl-4-methylphenyl)
Good heat stability and N resistance when formed into a molded product containing pentaerythritol-di-phosphite
An object of the present invention is to provide a block copolymer resin composition having OX properties and color tone stability.

In the above (A), 2-t-amyl-6- [1-
(3,5-di-t-amyl-2-hydroxyphenyl)
Ethyl] -4-t-amylphenyl acrylate was added in an amount of 0.05 to 100 parts by weight of the block copolymer.
To 2.0 parts by weight, preferably 0.10 to 1.0 part by weight. If the addition amount is less than 0.05 parts by weight, the effect of heat stability and color tone stability is poor and not practical, and if it exceeds 2.0 parts by weight,
It is not preferable because bleeding easily occurs.

The range of addition of the phenolic antioxidant of the above (B) is in the range of 20% by weight to 75% by weight of the amount of the above (A), that is, based on 100 parts by weight of the block copolymer.
It is 0.01 to 1.5 parts by weight, preferably 0.01 to 0.9 parts by weight. When the amount is less than 0.01 part by weight, the effects of heat stability and color tone stability are poor.
OX yellowing is undesirably reduced.

The range of addition of the phosphorus antioxidant (C) is as follows:
The amount is 0.01 to 2.0 parts by weight, preferably 0.05 to 1.0 part by weight, based on 100 parts by weight of the block copolymer. The amount added
If the amount is less than 0.01 part by weight, the effects of thermal stability and color tone stability are poor, and the effect is not practical. If the amount is more than 2.0 parts by weight, bleeding tends to occur, which is not preferable.

The block copolymer of the present invention comprises:
The number average molecular weight of the vinyl aromatic hydrocarbon polymer block defined by the following formula is 3,000 to 100,000,
The block ratio is 40 to 95%, and the 1,2-vinyl content in the conjugated diene microcomposition is 15% or more.

As a method for measuring the number average molecular weight of the vinyl aromatic hydrocarbon polymer block, there is an ozonolysis method.
Examples of the method of measuring the block rate include a decomposition method using osmium oxide, an NMR method, an ozonolysis method, and the like.

As a method for measuring the 1,2-vinyl content in the microstructure of a conjugated diene, there is an IR method.

Block ratio = [weight of all vinyl aromatic hydrocarbon polymer blocks in block copolymer / weight of total vinyl aromatic hydrocarbon polymer in block copolymer] × 1
00

The block copolymer is represented by the general formula: (SB) n B- (SB) n S- (B） S) n [(SB) n] mx [S- (B─) S) n] mx [B- (SB) n] mx (where S is a vinyl aromatic hydrocarbon polymer block, and B is a vinyl aromatic hydrocarbon and a conjugated diene , A random block composed of a vinyl aromatic hydrocarbon and a conjugated diene, or a sequence composed of a random portion and a conjugated diene block.
X represents a residue of a coupling agent or a residue of a polyfunctional organolithium compound. N and m represent an integer of 1 to 10. ) Etc.

The number average molecular weight of the block copolymer is 40,
The melt flow according to JIS K-6870 is preferably from 0.1 to 25 g / 10 minutes.

The number average molecular weight of the vinyl aromatic hydrocarbon polymer block is in the range of 3,000 to 100,000.

The block copolymer in the present invention is obtained by copolymerizing a vinyl aromatic hydrocarbon monomer and a conjugated diene monomer in a hydrocarbon solvent with an organic lithium compound as an initiator.

The vinyl aromatic hydrocarbon monomers include styrene, α-methylstyrene, vinyltoluene and the like.

Examples of the conjugated diene monomer include 1,3 butadiene and isoprene.

Examples of the hydrocarbon solvent include benzene, ethylbenzene, toluene, hexane, cyclohexane, heptane and the like.

Next, as a method for removing the solvent from the polymerization solution, there is a steam stripping method, a method of directly devolatilizing using a twin screw extruder, a thin film evaporator, a drum dryer or the like.

The block copolymer resin composition of the present invention comprises:
1 is selected from other phosphorus-based antioxidants if necessary.
The thermal stability can be further improved by adding 0.05 to 1.0 part by weight, preferably 0.05 to 0.8 part by weight, based on 100 parts by weight of the block copolymer.

Other phosphorus compounds include 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, tris (2,4-di-t-butylphenyl phosphite), tris (nonyl) Phenyl) phosphite and the like.

Also, the block copolymer resin of the present invention includes:
Other polymers can be blended if necessary. Other polymers include polystyrene, impact-resistant polystyrene, styrene-acrylic resin (styrene-acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-acrylic acid copolymer, etc.), ABS, For example, polypropylene.

The block copolymer of the present invention may contain, if necessary, an ultraviolet absorber, a hindered amine-based light stabilizer, a lubricant, a pigment, a filler, and the like. , An inorganic acid, carbon dioxide gas or the like may be added.

The block copolymer resin composition of the present invention is used for injection molding of various containers, caps, cassette halves, medical equipment, etc., for thermoforming, and for carrier tape because of its transparency and toughness. There are a wide range of fields such as sheets, shrink films, laminating films, films for keeping freshness of fruits and vegetables, and the like.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. SB, A-1 to A-4 and P-1 to P shown in Table-2
All numerical values used for -4 represent parts by weight. Examples 1 to 7 n- in dehydrated cyclohexane under a nitrogen gas atmosphere
A block copolymer having a styrene content of 80% by weight and having an SB structure was synthesized using BuLi as a catalyst. 75 l of dehydrated cyclohexane, 8 kg of styrene monomer, and 40 g of tetrahydrofuran were charged into a 100 l polymerization vessel, and 0.15 mmol of n-BuLi was further added to carry out polymerization. Next, 8 kg of a styrene monomer and 4 kg of dry butadiene were added and polymerized. Table 1 shows the measurement results of the obtained block copolymer.

Example 8 To the same polymerization solution as in Example 1, phenolic and P-1 and P-3 phosphorus antioxidants were added according to the formulation shown in the upper part of Table 2, and the solvent was directly removed. After removal by volatility,
P-4 phosphorus antioxidant was added, and polymer pellets were obtained with an extruder. The physical properties of this polymer pellet are shown in the lower part of Table-2.

Example 9 To the same polymerization solution as in Example 1, phenolic and P-1 phosphorus antioxidants were added according to the formulation shown in the upper part of Table 2, and the solvent was removed by direct devolatilization. After that, a phosphorus-based antioxidant of P-4 was added, and polymer pellets were obtained with an extruder. The physical properties of this polymer pellet are shown in the lower part of Table-2.

Example 10 To the same polymerization solution as in Example 1, phenolic and P-1 phosphorus antioxidants were added according to the formulation shown in the upper part of Table 2, and the solvent was directly removed by devolatilization. Thereafter, a styrene resin (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Denkastyrol GP-1) was blended, and polymer pellets were obtained with an extruder. Table 1 shows the compounding ratio and the physical properties of the polymer pellets.
2 Shown at the bottom.

Comparative Examples 1 to 3 n-dehydrated cyclohexane in a nitrogen gas atmosphere
A block copolymer having the structure shown in Table 1 was synthesized using BuLi as a catalyst. A phenol-based and phosphorus-based antioxidant was added to the polymerization solution according to the formulation shown in the upper part of Table 2, and the solvent was directly removed by devolatilization to obtain polymer pellets using an extruder. Table 1 shows the physical properties of the polymer pellets.
2 Shown at the bottom.

Comparative Example 4 A phenolic antioxidant was added to the same polymerization solution as in Example 1 according to the formulation shown in the upper part of Table 2, and the solvent was directly removed by devolatilization. A phosphorus-based antioxidant was added, and polymer pellets were obtained with an extruder. The physical properties of this polymer pellet are shown in the lower part of Table-2.

Comparative Example 5 Phosphorus antioxidants of phenol type and P-3 were added to the same polymerization solution as in Example 1 according to the formulation shown in the upper part of Table 2, and the solvent was directly removed by devolatilization. After that, a phosphorus-based antioxidant of P-4 was added, and polymer pellets were obtained with an extruder. The physical properties of this polymer pellet are shown in the lower part of Table-2.

Table 1 Block structure: S—B S: Styrene polymer block B: Styrene-butadiene polymer tapered block Butadiene polymer content (Note 1): 20.1% by weight Number average molecular weight of block copolymer (Note) 2): 166,000 Number average molecular weight of styrene polymer block (Note 3): 42,000 Block ratio of styrene polymer (Note 4): 83% 1,2 vinyl content in butadiene polymer (Note 5): 23% ( * 1 Butadiene content: measured by halogen addition method * 2: Measured by gel permeation chromatography * 3: Measured by ozonolysis method * 4: Measured by NMR method * 5: Measured by IR method

[0036]

[Table 2]

1. Formulation (1) SB: Styrene-butadiene block copolymer (2) A-1: 2-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl ] -4
-T-amylphenyl acrylate (3) A-2: 2-t-butyl-6- (3-t-butyl-
2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (4) A-3: 3,9-bis [1,1-dimethyl-2-
{Β- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl] -2,4
8,10-tetraoxaspiro [5,5] undecane (5) A-4: n-octadecyl-3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionate (6) P-1: bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite (7) P-2: 2,2 -Methylenebis (4,6-di-t-
(8) P-3: tris (2,4-di-t-butylphenyl phosphite) (9) P-4: tris (nonylphenyl) phosphite

2. Physical properties (1) Optical properties: A 2 mm-thick plate-like molded product was molded using an injection molding apparatus to obtain a measurement sample. Haze: ASTM D-1003 Gloss: ASTM D-523 Hue ΔE: JIS K-7105, device: ND-1001-DP manufactured by Nippon Denshoku Industries Co., Ltd.

(2) Thermal stability: Using an injection molding apparatus,
After the resin was allowed to stay in the cylinder at 250 ° C. for 20 minutes, a plate-shaped molded product having a thickness of 2 mm was formed to obtain a measurement sample. Haze: ASTM D-1003 Gloss: ASTM D-523

(3) Yellowing resistance: A 2 mm-thick plate was molded using an injection molding apparatus to obtain a measurement sample for a Nox exposure test. Hue YI: Based on JIS L0855, Nox; 1 Vo
1% for 6 hours

(4) Number of fish eyes: A film having a thickness of 50 μm was formed by the inflation method and 500 c
Seven samples of m ² (10 cm × 50 cm) were cut out to make a sample, and the number of fish eyes in the film was counted using a colony counter manufactured by ELM, and the average value was determined. Inflation film forming conditions: BUR = 2.0, DUR = 1
2

[0042]

As described above, the present invention provides a resin composition by using a block copolymer in combination with a different type of antioxidant to obtain a resin composition having a high thermal stability during injection molding. The molded product obtained is excellent in optical properties and environmental resistance (yellowing resistance in outdoor exposure). Further, the resin composition of the present invention also has a feature that fish eyes on the film are reduced even when the film is formed.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 53/00-53/02 C08K 5/13 C08K 5/524

Claims (1)

(57) [Claims] 1. A polymer mixture containing a vinyl aromatic hydrocarbon-conjugated diene block copolymer or a vinyl aromatic hydrocarbon-conjugated diene block copolymer,
The vinyl aromatic hydrocarbon-conjugated diene block copolymer has a vinyl aromatic hydrocarbon content of 60 to 95% by weight, a conjugated diene content of 5 to 40% by weight, and the number of vinyl aromatic hydrocarbon polymer blocks. Average molecular weight of 3,000-1
00000 and the block rate is 40-95%,
In addition, (A) 2-t-amyl-6- [1- (3,5) is added to 100 parts by weight of the block copolymer having a 1,2-vinyl content of 15% or more in the microstructure of the conjugated diene. -Di-t-amyl-2-hydroxyphenyl) ethyl] -4-t-amylphenyl acrylate at 0.05 to 2.0 parts by weight (B) at least one compound selected from the following phenolic antioxidants at 0.01 to 1.5 parts by weight 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate, n-octadecyl-3- (3,5-di-tert-butyl) -4-hydroxyphenyl) propionate or 3,9-bis [1,1-dimethyl-2- {β- (3-t
-Butyl-4-hydroxy-5-methylphenyl) propionyloxydiethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane and (C) the following phosphorus-based antioxidants 0.01 to 2.0 parts by weight bis (2,6-di-t-butyl-4-methylphenyl)
A resin composition containing pentaerythritol-di-phosphite was used as a 2 mm-thick plate-like molded product having a haze of 1 according to ASTM D-1003.
A block copolymer resin composition having a YI value of less than 0% and a YI value of less than 10% as measured according to JIS K-7105.